feature request: add option useLivejs

[schlichtanders]

There is already lovely support for live updates for html http://livejs.com/

The only limitation is that it does not work for file:/// protocol, however that is not a problem at all in many cases as you can easily setup a local file server. In Intellij Idea this is already automatically done.

The only changes which need to be applied are

• adding a new Boolean function argument to the plot function, useLivejs for instance

• like done with the useCdn flag, when useLivejs==true, the header below has to be appended inside the head tag

  <script type="text/javascript" src="http://livejs.com/live.js"></script>